JNCIA-DevOps Practice Test 23 — 15 Questions

Question 1

Which TWO statements are true regarding NETCONF locking mechanisms on Junos devices? (Choose two)

Accepted Answer

If a NETCONF session terminates unexpectedly, any locks held by that session are automatically released by the device.. Locks prevent concurrent configuration edits and can be released via explicit unlock or session termination.

Answer

Multiple concurrent NETCONF sessions can obtain exclusive write locks on the candidate datastore at the same time.

Answer

Locks can only be released by rebooting the Routing Engine.

Answer

Locking is strictly mandatory for every single <get-config> request.

Question 2

An automation engineer is designing a Junos XML API workflow that uses the <get-config> operation. Which THREE parameters or filtering methods are valid when retrieving configuration data from a Junos device using NETCONF? (Choose three.)

Accepted Answer

Specifying the source datastore (e.g., ).. Valid filtering and parameter methods for include specifying the target datastore source, applying subtree filtering, and using xpath-based filters under specific namespace conditions.

Answer

Using SQL queries enclosed in <sql-query> tags to extract table rows directly from the configuration database.

Answer

Using the attribute within the tag to limit configuration tree traversal.

Question 3

Which TWO tools or protocols can be used to interact with the Junos XML API besides NETCONF over SSH? (Choose two)

Accepted Answer

Junos PyEZ library. Junos XML API can be accessed via NETCONF over SSH or via HTTP/HTTPS using the Junos XML API over HTTP server.

Answer

Syslog over UDP port 514

Answer

RADIUS authentication protocol

Answer

SNMP v3 traps

Question 4

Which TWO conditions will cause a NETCONF <edit-config> transaction to fail on a Junos device? (Choose two)

Accepted Answer

Syntax errors in the XML payload structure.. Transactions fail due to syntactic errors, missing required fields, or validation failures.

Answer

Executing a successful <commit> immediately after editing.

Answer

Using a valid namespace prefix declared in the NETCONF hello message.

Answer

Locking the candidate datastore prior to making edits.

Question 5

Which THREE attributes are available within the <edit-config> operation element in NETCONF to specify the modification action on a target node? (Choose three)

Accepted Answer

delete. NETCONF edit-config operation attributes include merge, replace, create, delete, and remove.

Answer

append

Answer

modify

Question 6

You need to execute a custom remote procedure call (RPC) in PyEZ to retrieve the Ethernet switching table. The tag in Junos XML API is get-ethernet-switching-table-information. How should you write this method call in Python?

Accepted Answer

dev.rpc.get_ethernet_switching_table_information(). PyEZ maps XML RPC hyphens to Python underscores, allowing you to call rpc methods directly as attributes on dev.rpc.

Answer

dev.rpc.get-ethernet-switching-table-information()

Answer

dev.get_ethernet_switching_table_information()

Answer

dev.execute_rpc('get-ethernet-switching-table-information')

Question 7

When executing a PyEZ RPC call that returns a large dataset (e.g., massive routing table), how can you handle the output efficiently without exhausting local memory?

Accepted Answer

Using parser generators or iterator arguments supported by specific RPC wrappers. Using generators or streaming options in RPC handling prevents loading massive XML trees entirely into memory.

Answer

etree.iterparse() directly on the raw socket stream

Answer

dev.rpc.get_route_information(normalize=True)

Answer

dev.stream_rpc()

Question 8

Which user credential validation mechanism does the Junos REST API use by default when authenticating incoming API calls?

Accepted Answer

Junos local user database or AAA via HTTP Basic Authentication. The Junos REST API authenticates incoming requests against the Junos local user database or configured AAA servers (RADIUS/TACACS+) using standard HTTP Basic Authentication.

Answer

OAuth 2.0 bearer tokens generated by an external IdP

Answer

Pre-shared API secret keys stored in environment variables

Answer

SSH public key authentication exclusively

Question 9

When sending an HTTP POST request to create a new configuration resource via the Junos REST API, what happens if the resource already exists in the candidate configuration?

Accepted Answer

The request is rejected, typically returning a 409 Conflict status code.. In standard REST semantics and Junos REST implementation, a POST request to an existing resource may result in a conflict error (such as HTTP 409 Conflict) or duplicate creation error if the identifier already exists, whereas PUT is idempotent and overwrites.

Answer

The device automatically performs an HTTP DELETE followed by a POST.

Answer

The device silently ignores the request and returns 200 OK.

Answer

The existing resource is converted to an operational state counter.

Question 10

When comparing the workflow and capabilities of the Junos REST API versus NETCONF, which THREE statements are correct? (Choose three)

Accepted Answer

NETCONF requires explicit and RPC workflows, whereas REST API abstracts transaction locking implicitly.. NETCONF uses SSH port 830 and XML RPCs with explicit candidate locking, whereas Junos REST API uses HTTP/HTTPS (port 3000/3443) and supports JSON and XML resource operations.

Answer

Junos REST API only supports JSON format, while NETCONF only supports binary streams.

Answer

NETCONF does not support commit operations, whereas REST API automatically commits every keystroke.

Question 11

When implementing Jinja2 templates for Junos configuration generation, which THREE features or syntax constructs are natively supported by the Jinja2 engine?

Accepted Answer

Variable substitution using double curly braces (e.g., {{ interface_name }}). Jinja2 natively supports variable interpolation using double curly braces, control structures like for-loops using {% for %}, and template inheritance via {% extends %}. Options A, C, and D are correct.

Answer

Automatic translation of Jinja2 syntax into NETCONF XML filters without evaluation

Answer

Direct execution of arbitrary host-level Bash shell scripts inside template bodies

Question 12

In JSNAPy, what file format is used to define test cases and expected operational states?

Accepted Answer

YAML. JSNAPy uses YAML configuration files for defining tests and expected values.

Answer

INI

Answer

XML

Answer

JSON

Question 13

You are utilizing PyEZ Table and View abstractions to parse interface statistics. Which base class must your custom Table class inherit from to map to Junos XML output?

Accepted Answer

jnpr.junos.factory.Table. To leverage PyEZ Table/View mapping for operational commands, your custom table class must inherit from 'jnpr.junos.factory.Table'.

Answer

jnpr.junos.rpchandler.RPC

Answer

jnpr.junos.device.Device

Answer

jnpr.junos.utils.config.Config

Question 14

You are writing a script that uses PyEZ to load a partial configuration merge. By default, what configuration database mode does the Config utility lock and load into?

Accepted Answer

The candidate configuration database. By default, PyEZ loads configuration changes into the candidate configuration database.

Answer

The rescue configuration database

Answer

A private configuration database instance

Answer

The global active configuration database

Question 15

Which TWO of the following methods or attributes are valid ways to handle rollback operations or commit errors when using the PyEZ Config utility (cu)?

Accepted Answer

cu.rollback(id=1). cu.rollback() reverts the candidate configuration to a previous rollback index, and cu.commit(comment=...) allows committing changes with specific options. Options B and D are correct.

Answer

cu.force_commit()

Answer

cu.undo()

Answer

cu.revert(rollback=0)